Modified polysiloxanes, rubber compositions and tire tread rubber compositions containing the same, and reactive plasticizer

ABSTRACT

A polysiloxane having a siloxane structure of the following formulas (1) and (2): ##STR1## wherein, R 1  is a C 1  to C 6  alkyl group or C 1  to C 21  acyl group, a is 1 to 200, b is 1 to 200, t is 2 or 3 and r is 1 to 100, and a rubber composition containing the same.

TECHNICAL FIELD

The present invention relates to a modified polysiloxane and to a rubbercomposition and a tire tread rubber composition using the same. Moreparticularly, it relates to a modified polysiloxane which is free frommigration from rubber due to the formulation of the modifiedpolysiloxane in a rubber composition and, as compared with ordinaryplasticizers, gives a low modulus, improves the processability of asilica formulated rubber, reduces the temperature dependency of thehardness, is superior in the tans balance, and enables an improvement inthe grip on ice/snow, abrasion resistance, etc. and to a rubbercomposition and a tire tread rubber composition using the same.

Further, the present invention relates to a non-migratory reactiveplasticizer used in a rubber or a resin composition, more particularlyto a siloxane-based reactive plasticizer suitable for use in a rubber ora resin composition containing silica, clay, mica, kaolin, active clay,or other silicon-containing fillers.

BACKGROUND ART

In general, plasticizers are used for many products comprising rubbercompositions. These migrate with the passage of time, and therefore,there has been the problem of changes in the performance of the productwith the elapse of time. To deal with this problem, it is known to addliquid IR or BR, but these are not necessarily covulcanized andconsiderably migrate.

Further, since these are diene polymers, the heat aging resistance etc.deteriorates.

Further, there is the technique of adding a plasticizer for the purposeof reducing the hardness of the rubber at a low temperature (seeJapanese Unexamined Patent Publication (Kokai) No. 6-116443), but theplasticizer per se has a high volatility and migration property, andtherefore, there is a large change with time and the performance on iceis considerably decreased. Further, if a large amount of the plasticizeris formulated, there is a problem that the abrasion resistance is alsodecreased.

Further, there is the technique of formulating a butyl rubber or ahalogenated butyl rubber into a tire tread rubber composition so as toimprove the grip performance on ice (see Japanese Unexamined PatentPublication (Kokai) No. 60-213506 and Japanese Unexamined PatentPublication (Kokai) No. 5-001177), but there is a defect that theabrasion resistance is conversely decreased.

Further, many plasticizers are used for various types of rubber andresins. Among these, since ester-based plasticizers are in particularsuperior in compatibility with rubber and resins, they have been usedconventionally in the past. However, these ester compounds do not reactwith rubber or resins or with fillers and migrate to the outside withthe elapse of time, and therefore, there was the problem that theycaused the physical properties of the rubber or resins to fall with thepassage of time. Further, reactive plasticizers for epoxy resins arewell known, but almost no reactive plasticizers for other resins orrubber are known.

DISCLOSURE OF THE INVENTION

Accordingly, an object of the present invention is to provide a specificpolysiloxane modified with a liquid polymer which, when formulated inmost rubber compositions, particularly rubber compositions containingcarbon black and/or silica, does not migrate and also gives a curedrubber which is flexible even at low temperatures and improves theprocessability when unvulcanized.

Another object of the present invention is to provide a tire treadrubber composition which, by formulating a modified polysiloxane in atire tread rubber composition, can maintain a low modulus, can reducethe temperature dependency of the hardness, is superior in the tansbalance, and is improved in the gripping force on ice/snow, the abrasionresistance, etc.

Still another object of the present invention is to provide a reactiveplasticizer for preventing deterioration in the physical properties of arubber or a resin composition with the passage of time.

According to the present invention, as the specific polysiloxanemodified with a liquid polymer, there are provided a polysiloxane havingthe siloxane structure of the following formulas (1) and (2) and apolysiloxane having the siloxane structure of the following formulas (1)and (3): ##STR2## wherein, R¹ is a C₁ to C₆ alkyl group or C₁ to C₂₁acyl group, R² is a C₂ to C₄ alkylene group, R³ is a monovalenthydrocarbon group, a is 1 to 200, b is 1 to 200, c is 1 to 200, t is 2or 3, r is 1 to 100, and s is 1 to 100.

Further, according to the present invention, there is provided a rubbercomposition comprising 100 parts by weight of rubber and 1 to 50 partsby weight of a polysiloxane having a siloxane structure of the aboveformulas (1) and (2) and/or a polysiloxane having a siloxane structureof the above formulas (1) and (3) formulated therein, and particularlysaid rubber composition further comprising silica formulated therein.

Further, according to the present invention, there is provided a tiretread rubber composition comprising 100 parts by weight of at least onerubber selected from the group consisting of natural rubber,polybutadiene rubber, styrene-butadiene copolymer rubber, andpolyisoprene rubber and 45 to 80 parts by weight of at least one fillerselected from the group consisting of carbon blacks having a specificsurface area by nitrogen adsorption (N₂ SA) of 50 to 170 m² /g and adibutyl phthalate oil absorption (DBP) of 60 to 140 ml/100 g or otherfillers, 5 to 50 parts by weight of a polysiloxane having a siloxanestructure of the above formulas (1) and (2) and/or a polysiloxane havinga siloxane structure of the above formulas (1) and (3), and a softeningagent and other rubber chemicals are formulated therein.

Further, according to the present invention, there is provided a tiretread rubber composition comprising 100 parts by weight of at least onerubber selected from the group consisting of natural rubber,polybutadiene rubber, styrene-butadiene copolymer rubber, andpolyisoprene rubber in which 20 to 60 parts by weight of at least onefiller selected from the group consisting of carbon blacks having aspecific surface area by nitrogen adsorption (N₂ SA) of 50 to 170 m² /gand a dibutyl phthalate oil absorption (DBP) of 60 to 140 ml/100 g, 5 to50 parts by weight of at least one filler selected from the groupconsisting silicas having a specific surface area by nitrogen adsorption(N₂ SA) of 80 to 300 m² /g and a dibutyl phthalate oil absorption (DBP)of 100 to 300 ml/100 g, 5 to 50 parts by weight of a polysiloxane havinga siloxane structure of the above formulas (1) and (2) and/or apolysiloxane having a siloxane structure of the above formulas (1) and(3), and a softening agent and other rubber chemicals are formulated.

Further, according to the present invention, there is provided a tiretread rubber composition comprising 100 parts by weight of at least onerubber selected from the group consisting of styrene-butadiene copolymerrubbers having a styrene content in the range of at least 10% by weightand 60 to 100 parts by weight of at least one filler selected from thegroup consisting of carbon blacks having a specific surface area bynitrogen adsorption (N₂ SA) of 50 to 170 m² /g and a dibutyl phthalateoil absorption (DBP) of 70 to 140 ml/100 g or other fillers, 5 to 50parts by weight of a polysiloxane having a siloxane structure of theabove formulas (1) and (2) and/or a polysiloxane having a siloxanestructure of the above formulas (1) and (3), and a softening agent andother rubber chemicals formulated therein.

Further, according to the present invention, there is provided a tiretread rubber composition comprising 100 parts by weight of at least onerubber selected from the group consisting of styrene-butadiene copolymerrubbers having a styrene content in the range of at least 10 wt %, inwhich 20 to 80 parts by weight of at least one filler selected from thegroup consisting of carbon blacks having a specific surface area bynitrogen adsorption (N₂ SA) of 50 to 170 m² /g and a dibutyl phthalateoil adsorption (DBP) of 70 to 140 ml/100 g, 5 to 50 parts by weight ofat least one filler selected from the group consisting of silicas havinga specific surface area by nitrogen adsorption (N₂ SA) of 80 to 300 m²/g and a dibutyl phthalate oil absorption (DBP) of 100 to 300 ml/100 g,5 to 50 parts by weight of a polysiloxane having a siloxane structure ofthe above formulas (1) and (2) and/or a polysiloxane having a siloxanestructure of the above formulas (1) and (3), and a softening agent andother rubber chemicals are formulated.

Further, according to the present invention, there is provided a rubbercomposition comprising 100 parts by weight of at least one rubberselected from the group consisting of natural rubber, polybutadienerubber, styrene-butadiene copolymer rubber, and polyisoprene rubber inwhich 45 to 80 parts by weight of at least one filler selected from thegroup consisting of carbon black having a specific surface area bynitrogen adsorption (N₂ SA) of 50 to 170 m² /g and a dibutyl phthalateoil absorption (DBP) of 60 to 140 ml/100 g or other fillers, 2 to 150parts by weight of (a) a silica-containing polysiloxane master batchcomprising 100 parts by weight of at least one ingredient selected fromthe group consisting of polysiloxanes having a siloxane structure of theabove formulas (1) to (3) containing 30 to 200 parts by weight of atleast one filler selected from the group consisting of silicas having aspecific surface area by nitrogen adsorption (N₂ SA) of 80 to 300 m² /gand a dibutyl phthalate oil absorption (DBP) of 100 to 300 ml/100 g, (b)a carbon black-containing polysiloxane master batch comprising 100 partsby weight of at least one ingredient selected from the group consistingof polysiloxanes having a siloxane structure of the above formulas (1)to (3) containing 30 to 200 parts by weight of at least one fillerselected from the group consisting of carbon blacks having a specificsurface area by nitrogen adsorption (N₂ SA) of 50 to 170 m² /g and adibutyl phthalate oil absorption (DBP) of 60 to 140 ml/100 g or otherfillers, or (c) a silica- and carbon black-containing polysiloxanemaster batch comprising a mixture comprising 100 parts by weight of atleast one ingredient selected from the group consisting of polysiloxaneshaving a siloxane structure of the above formulas (1) to (3) containing1 to 199 parts by weight of at least one filler selected from the groupconsisting of carbon blacks having a specific surface area by nitrogenadsorption (N₂ SA) of 50 to 170 m² /g and a dibutyl phthalate oilabsorption (DBP) of 60 to 140 ml/100 g or other fillers and 1 to 199parts by weight of at least one filler selected from the groupconsisting of silicas having a specific surface area by nitrogenadsorption (N₂ SA) of 80 to 300 m² /g and a dibutyl phthalate oilabsorption (DBP) of 100 to 300 ml/100 g, wherein the sum of the two is30 to 200 parts by weight, and a softening agent and other rubberchemicals are formulated.

Further, according to the present invention, there is provided a rubbercomposition comprising of 100 parts by weight of at least one rubberselected from the group consisting of styrene-butadiene copolymershaving a styrene content of at least 10% by weight in which 60 to 100parts by weight of at least one filler selected from the groupconsisting of carbon blacks having a specific surface area by nitrogenadsorption (N₂ SA) of 50 to 170 m² /g and a dibutyl phthalate oilabsorption (DBP) of 70 to 140 ml/100 g or other fillers, 2 to 150 partsby weight of (a) a silica-containing polysiloxane master batchcomprising 100 parts by weight of at least one ingredient selected fromthe group consisting of polysiloxanes having a siloxane structure of theabove formulas (1) to (3) containing 30 to 200 parts by weight of atleast one filler selected from silicas having a specific surface area bynitrogen adsorption (N₂ SA) of 80 to 300 m² /g and a dibutyl phthalateoil absorption (DBP) of 100 to 300 ml/100 g, (b) a carbonblack-containing polysiloxane master batch comprising 100 parts byweight of at least one ingredient selected from the group consisting ofpolysiloxanes having a siloxane structure of the above formulas (1) to(3) containing 30 to 200 parts by weight of at least one filler selectedfrom the group consisting of carbon blacks having a specific surfacearea by nitrogen adsorption (N₂ SA) of 50 to 170 m² /g and a dibutylphthalate oil absorption (DBP) of 60 to 140 ml/100 g or other fillers,or (c) a silica- and carbon black-containing polysiloxane master batchcomprising a mixture comprising 100 parts by weight of at least oneingredient selected from the group consisting of polysiloxanes having asiloxane structure of the above formulas (1) to (3) containing 1 to 199parts by weight of at least one filler selected from the groupconsisting of carbon blacks having a specific surface area by nitrogenadsorption (N₂ SA) of 50 to 170 m² /g and a dibutyl phthalate oilabsorption (DBP) of 60 to 140 ml/100 g or other fillers and 1 to 199parts by weight of at least one filler selected from the groupconsisting of silicas having a specific surface area by nitrogenadsorption (N₂ SA) of 80 to 300 m² /g and a dibutyl phthalate oilabsorption (DBP) of 100 to 300 ml/100 g, wherein the sum of the two is30 to 200 parts by weight, and a softening agent and other rubberchemicals are formulated.

Further, according to the present invention, there is provided asiloxane-based reactive plasticizer having, as a plasticizer ingredient,at least 50 wt % of an organic group containing an ester group or analiphatic or aromatic hydrocarbon group and having as a reactive groupin a molecule at least one of an alkoxysilyl group and an acyloxysilylgroup.

Further, according to a preferable embodiment of the present invention,there is provided a siloxane-based plasticizer, that is, a polysiloxanehaving in a molecule at least one siloxane unit of the following formula(I) and formula (II): ##STR3## wherein, R¹ is a C₁ to C₆ alkyl groupand/or C₁ to C₂₁ acyl group, R² is a C₂ or C₃ alkylene group, R³ is a C₅to C₂₁ hydrocarbon group, and R⁴ is a C₆ to C₂₀ hydrocarbon group.

BEST MODE FOR WORKING THE INVENTION

The constitution and working-effect of the present invention will beexplained below.

As the polyisobutylene-containing alkoxy or acyloxypolysiloxane of thepresent invention, the following compounds A to C may be illustrated:##STR4##

These polysiloxanes are, for example, synthesized as follows: Thesynthesis can be carried out by reacting a polysiloxane having an Si--Hgroup with an alcohol or a carboxylic acid, and then reacting apolyisobutylene having an alkenyl group at an end with this reactionproduct. As a catalyst of this reaction, a transition metal catalyst ofthe Group VIII of the Periodic Table can be used. In particular, it ispreferable to use a platinum chloride, an olefin complex, etc.

As the polysiloxane having an Si--H group, the following containingdimethyl siloxane units may be illustrated: ##STR5##

In the formulas, n is not particularly limited, but, industrially, thereis no product with single molecular-weight distribution of n's.Polysiloxanes with a certain width of molecular-weight distributionrelating to n's, that is, in general with n's of not more than 100,particularly around 40, are commercially available. Further, m is notparticularly limited, but polysiloxanes with m's of 1 to 100 can beeasily obtained. Polysiloxanes with x's of 3 to 6, particularly 4, areavailable, while polysiloxanes with y's and z's of 1 or more and withtotals of y+z of not more than 6 are known.

These polysiloxane can be used equivalently for the purpose of thepresent invention and may be used alone or as mixtures.

As the alcohol, methanol, ethanol, propanol, butanol, pentanol, hexanol,etc. may be illustrated. In particular, methanol, ethanol, and propanolmay be preferably used.

As the carboxylic acid, for performance purposes, saturated,unsaturated, aliphatic, and aromatic carboxylic acids from formic acidhaving one carbon to behenic acid having 22 carbon atoms may be used,but from the viewpoint of odor and price, palmitic acid, stearic acid,or their mixtures are preferably used.

As the polyisobutylene having an alkenyl group at its end, the followingmay be used: ##STR6##

When the r in the formula is 1 to 100, the polymeric compound becomeseasy to handle viscosity-wise.

As the method of synthesis of these polysiloxanes, first, a polysiloxanehaving an Si--H group may be reacted with an alcohol or carboxylic acid,then reacted with an alkenyl group-terminated polyisobutylene or analkenyl group-containing silicon may be reacted with a polysiloxanehaving an Si--H group, then reacted with an alkenyl group-terminatedpolyisobutylene or these may be reacted simultaneously.

To achieve the objects of the present invention, other siloxane unitsmay also be contained, but in this case, it is necessary to include atleast 40 wt % of polyisobutylene.

Further, as the polyether containing alkoxy or acyloxypolysiloxane ofthe present invention, the following a compounds D to E may beexemplified: ##STR7##

These polysiloxanes may be synthesized in the same way as the abovepolyisobutylene-containing alkoxy or acyloxy polysiloxane. That is, theymay be synthesized by reacting the above polysiloxane having an Si--Hgroup with an alcohol or carboxylic acid and the following alkenylterminated polyether, or by reacting the above polysiloxane having anSi--H group with an alkenyl group-containing silicon and alkenylterminated polyether. As the catalyst of this reaction, a Group VIIItransition metal catalyst, in particular a platinum chloride, an olefincomplex, etc., may be also preferably used. ##STR8##

    CH.sub.2 ═CH--Si(OR.sup.1).sub.3 or

    CH.sub.2 ═CH--CH.sub.2 Si (OR.sup.1).sub.3

Wherein, s is 1 to 100, s₁ is 1 to 100, s₂ is 1 to 100, and S₁ +s₂ =s.Further, R¹ is a C₁ to C₆ alkyl group or C₁ to C₂₁ acyl group.

The above alkoxyl or acyloxysiloxane unit can combine with silica if atleast one unit is present in a molecule, and, as a result, thepolysiloxane is no longer bleeding out. However, the presence of atleast 2 units are particularly preferable.

To achieve the objects of the present invention, other siloxane unitsmay also be contained. In this case, the above polyether must becontained in an amount of at least 40% by weight.

The polyisobutylene-containing alkoxy or acyloxy polysiloxane and theabove polyether-containing alkoxy or acyloxy polysiloxane of the presentinvention may be used for a rubber composition comprised of variousformulations. This is used in an amount of 1 to 50 parts by weight,preferably an amount of 5 to 30 parts by weight, per 100 parts by weightof rubber. If the amount of the polysiloxane formulated is too small,the desired effect cannot be obtained, while if too large, problemsarise in the performance of the rubber.

The rubber component formulated into the rubber composition according tothe present invention is a cross-linkable rubber component alone or in amixture of two or more types. As the cross-linkable rubber, any rubbermay be used. For example, natural rubber (NR), various butadiene rubbers(BR), various styrene-butadiene copolymer rubbers (SBR), polyisoprenerubber (IR), butyl rubber (IIR), acrylonitrile-butadiene rubber,chloroprene rubber, ethylene-propylene copolymer rubbers,ethylene-propylene-diene copolymer rubbers, styrene-isoprene copolymerrubber, styrene-isoprene-butadiene copolymer rubber, isoprene-butadienecopolymer rubber, chlorosulfonated polyethylene, acryl rubber,epichlorohydrin rubber, polysulfide rubber, silicone rubber,fluororubber, urethane rubber, and the like may be used. When using ablend of the rubbers, the ratio of the blend is not particularlylimited.

According to the present invention, any carbon black and/or silicanormally formulated in a rubber composition is formulated in the rubbercomposition. The silica according to the present invention is notparticularly limited and may be a wet or dry silica or surface treatedsilica etc. Any silica with silanol groups remaining may be used.Further, a carbon black surface treated with silica may also be used.The amount formulated is 10 to 100 parts by weight based on 100 parts byweight of the rubber.

The rubber composition according to the present invention may furtherinclude ordinary vulcanization or cross-linking agents, vulcanization orcross-linking accelerators, various types of oil, antioxidants, fillers,plasticizers, softening agents, and other additives generally formulatedinto general rubbers. These formulations may be kneaded and vulcanizedby general methods to make a composition which is then vulcanized orcross-linked. The amounts of these additives added may be the amountsgenerally used in the past so long as they do not contravene the objectsof the present invention.

There are numerous examples of formulations of tire tread rubbercompositions according to the present invention. Giving the preferableexamples of formulations comprised of selected rubber components andother compounding agents in tire tread rubber compositions, thefollowing (A) to (D) may be mentioned.

(A) A tire tread rubber composition comprising 100 parts by weight of atleast one rubber selected from the group consisting of natural rubber,polybutadiene rubber, styrene-butadiene copolymer rubber, andpolyisoprene rubber in which 45 to 80 parts by weight of at least onefiller selected from the group consisting of carbon blacks having aspecific surface area by nitrogen adsorption (N₂ SA) of 50 to 170 m² /gand a dibutyl phthalate oil absorption (DBP) of 60 to 140 ml/100 g oranother filler (for example, silica, talc, clay, calcium carbonate,etc.), 5 to 50 parts by weight of a modified polysiloxane of the presentinvention, and a softening agent and other rubber chemicals areformulated.

(B) A tire tread rubber composition comprising 100 parts by weight of atleast one rubber selected from the group consisting of natural rubber,polybutadiene rubber, styrene-butadiene copolymer rubber, andpolyisoprene rubber in which 20 to 60 parts by weight of at least onefiller selected from the group consisting of carbon blacks having aspecific. surface area by nitrogen adsorption (N₂ SA) of 50 to 170 m² /gand a dibutyl phthalate oil absorption (DBP) of 60 to 140 ml/100 g, 5 to50 parts by weight of at least one filler selected from the groupconsisting of silicas having a specific surface area by nitrogenadsorption (N₂ SA) of 80 to 300 m² /g and a dibutyl phthalate oilabsorption (DBP) of 100 to 300 ml/100 g, 5 to 50 parts by weight of amodified polysiloxane of the present invention, and a softening agentand other rubber chemicals are formulated.

(C) A tire tread rubber composition comprising 100 parts by weight of atleast one rubber selected from the group consisting of styrene-butadienecopolymer rubbers having a styrene content of at least 10% by weight inwhich 60 to 100 parts by weight of at least one filler selected from thegroup consisting of carbon blacks having a specific surface area bynitrogen adsorption (N₂ SA) of 50 to 170 m² /g and a dibutyl phthalateoil absorption (DBP) of 70 to 140 ml/100 g or other fillers, 5 to 50parts by weight of a modified polysiloxane of the present invention, anda softening agent and other rubber chemicals are formulated.

(D) A tire tread rubber composition comprising 100 parts by weight of atleast one rubber selected from the group consisting of styrene-butadienecopolymer rubbers having a styrene content of at least 10% by weight inwhich 20 to 80 parts by weight of at least one filler selected from thegroup consisting of carbon blacks having a specific surface area bynitrogen adsorption (N₂ SA) of 50 to 170 m² /g and a dibutyl phthalateoil absorption (DBP) of 70 to 140 ml/100 g, 5 to 50 parts by weight ofat least one filler selected from the group consisting of silicas havinga specific surface area by nitrogen adsorption (N₂ SA) of 80 to 300 m²/g and a dibutyl phthalate oil absorption (DBP) of 100 to 300 ml/100 g,5 to 50 parts by weight of a modified polysiloxane of the presentinvention, and a softening agent and other rubber chemicals areformulated.

The rubber used as a rubber component in the tire tread rubbercompositions of the above (A) to (D) is selected, in particular, inaccordance with the requirements of the ice and snow performance andabrasion resistance. Further, the ranges of selection of the specificsurface area by nitrogen adsorption (N₂ SA) and the dibutyl phthalateoil absorption (DBP) of the carbon black and silica, and the givenamounts of formulating of the same are necessary for achieving a goodbalance between improvement of the abrasion resistance by carbon and theimprovement of the ice and snow/wet road performance by silica aimed atby the tire tread rubber composition of the present invention.

When formulating a polysiloxane having a siloxane structure of the aboveformulas (1) to (3) in a rubber, it is desirable to formulate the sameas a master batch in which carbon black and silica are premixed inpredetermined amounts. The method of mixing is preferably solutionmixing in a good solvent or mechanical mixing by an internal mixer(Banbury or kneader). If the above polysiloxane and carbon black andsilica are mixed together in advance, the desired effect can be furtherimproved by sufficiently combining the carbon black and silica andpromoting the dispersion of the polysiloxane in the rubber.

Further, when preparing the above master batch, if a predeterminedamount of a silane coupling agent is formulated into the abovepolysiloxane and carbon black and silica, the dispersion of the masterbatch is further promoted when formulating it in the rubber and thereinforcing property is increased. Further, if a predetermined amount ofa silanol condensation catalyst is formulated in, the silane couplingagent works effectively and the reinforcing property is furtherincreased.

When formulating silica as a filler in the tire tread rubbercompositions of the above (A) to (D), it is possible to formulate 5 to30% by weight of a silane coupling agent in the rubber compositionsbased on the amount of silica formulated. Further, in this case, it ispossible to formulate 0.05 to 50% by weight of a silanol condensationcatalyst based on the amount of the silane coupling agent formulated. Asthe silanol catalyst, a tin-based, amine-based or titanium-basedcatalyst is preferably used. In particular, a titanium-based catalyst ispreferred.

As the silane coupling agent used for a tire tread rubber compositioncontaining silica according to the present invention, it is possible touse any silane coupling agent used together with a silica filler in thepast. As typical examples, the following may be mentioned. Of these,bis-[3-(triethoxysilyl)-propyl]tetrasulfide andbis-[3-(triethoxysilyl)-propyl]disulfide are most preferred from theviewpoint of the processability.

    ______________________________________                                        Chemical name   Structural formula                                            ______________________________________                                        Vinyltrimethoxysilane                                                                         CH.sub.2 ═CHSi(OCH.sub.3).sub.3                             Vinyltriethoxysilane CH.sub.2 ═CHSi(OCH.sub.2 CH.sub.3).sub.3                            Vinyltris(2- CH.sub.2 ═CHSi(OCH.sub.2 CH.sub.2                           OCH.sub.3).sub.3                                                methoxyethoxy)silane                                                           - N-(2-aminoethyl)3-  aminopropylmethyl  dimethoxysilane                                     #STR9##                                                        - N-(2-aminoethyl)3- H.sub.2 NCH.sub.2 CH.sub.2 NH(CH.sub.2).sub.3                         Si(OCH.sub.3).sub.3                                             aminopropyltrimethoxy                                                         silane                                                                        3-aminopropyltrimethoxy H.sub.2 N(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3                        silane                                                          - 3-glycidoxypropyltri  methoxysilane                                                        #STR10##                                                       - 3-glycidoxypropylmethyl  dimethoxysilane                                                   #STR11##                                                       - 2-(3,4-  epoxycyclohexyl)ethyl  trimethoxysilane                                           #STR12##                                                       - 3-methacryloxypropyl  trimethoxysilane                                                     #STR13##                                                       - 3-mercaptopropyl HS(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3                    trimethoxylsilane                                                             3-aminopropyl H.sub.2 N(CH.sub.2).sub.3 Si(OCH.sub.2 CH.sub.3).sub.3                         triethoxysilane                                                 - bis-[3-(triethoxysilyl)-  propyl]tetrasulfide                                              #STR14##                                                       - bis-[3-(triethoxysilyl)-  propyl]disulfide                                                ##STR15##                                                    ______________________________________                                    

When formulating a silane coupling agent in a tire tread rubbercomposition containing silica in which the modified polysiloxane of thepresent invention is formulated, it is possible to use a smaller amountof the silane coupling agent per se compared with those in the past andit is possible to further improve the abrasion resistance. The amount ofthe silane coupling agent used in the present invention is preferably inthe above range. If the amount formulated is too small, the desiredeffect is not obtained. Contrary to this, if the amount is too large,scorching easily occurs during the mixing or extrusion process. Further,if the silanol condensation catalyst is used together with apredetermined amount of the above, the reaction of the silane couplingagent with the silica proceeds well, the effect of the silane couplingagent is further improved, and it is possible to reduce the amount ofthe expensive silane coupling agent used.

Next, the constitution and working-effect of the reactive plasticizer ofthe present invention will be explained. The siloxane-based reactiveplasticizer of the present invention may be obtained by reacting aplasticizing component, that is, an ester group containing organic groupor hydrocarbon group, for example, an arylester or vinylester of acarboxylic acid, or a 1-octene, isooctene, 1-decene, limonene,vinylcyclohexene, styrene, divinylbenzene, α-methylstyrene orα-methylstyrene dimer with a reactive group, that is, a methyl hydrogenpolysiloxane, a Si--H group-containing polysiloxane such as Si--Hterminated polydimethylsiloxane, which constitutes an alkoxysilyl groupand/or acyloxysilyl group, using a Group VIII transition metal catalystsuch as platinum, ruthenium, rhodium catalyst. Further, thesiloxane-based reactive plasticizer may be obtained by reacting saidcarboxylic acid ester or 1-octene, isooctene, limonene,vinylcyclohexene, styrene, divinylbenzene, α-methylstyrene, orα-methylstyrene diner with a trimethoxysilane or methyldimethoxysilaneusing the said catalyst, and then hydrolyzing and condensing thesecompounds.

The above carboxylic acid is not particularly limited, but for exampledicarboxylic acid such as a phthalic acid, adipic acid, sebacic acid,monocarboxylic acid such as oleic acid, linoleic acid, linolic acid,2-ethylhexanoic acid, benzoic acid may be mentioned.

As the above organic group, a 1-octene, isooctene, 1-decene, limonene,vinylcyclohexene, styrene, divinylbenzene, α-methylstyrene,α-methylstyrene dimer residual group may be mentioned.

As the alkoxysilyl group constituting the reactive group of the reactiveplasticizer of the present invention, a methoxysilyl, ethoxysilyl,propoxysilyl, or butoxysilyl group may be mentioned, but a methoxysilylor ethoxysilyl group is particularly preferred from the viewpoint ofreactivity. On the other hand, as the acyloxysilyl group, specifically,a silyl ester of acetic acid, 2-ethylhexanoic acid, palmitic acid,stearic acid, oleic acid, etc. may be mentioned, but the use of a C₆ ormore acyloxysilyl group is particularly preferable from the viewpoint ofthe odor.

The alkoxysilyl group and acyloxysilyl group constituting the reactivegroup of the reactive plasticizer of the present invention may beintroduced by reacting a metal salt of an alcohol or a carboxylic acid(for example, sodium ethoxide, sodium oleate) with a chlorosilyl group,or by reacting an alcohol or carboxylic group with a compound having anSi--H group in the presence of a transition metal catalyst such asplatinum catalyst.

As the reactive plasticizer of the present invention, specifically thefollowing compounds F to M may be mentioned: ##STR16##

As the rubber in which the reactive plasticizer of the present inventionis formulated, a rubber used in various rubber compositions in the past,for example, natural rubber (NR), polyisoprene rubber (IR), variouspolybutadiene rubbers (BR), various styrene-butadiene copolymer rubbers(SBR), acrylonitrile-butadiene copolymer rubbers (NBR), butyl rubber(IIR), ethylene-propylene copolymer rubbers (EPR, EPDM), etc. may bementioned. Further, as the resin, vinyl chloride, urethane, acryl,styrene resins, etc. may be mentioned.

The rubber or resin composition in which the reactive plasticizer of thepresent invention is formulated may contain various fillers (carbonblack, silicon-containing fillers such as silica, clay, mica, kaolin,activated clay, and calcium carbonate), vulcanizing or cross-linkingagents, vulcanization or cross-linking accelerators, oils, antioxidants,UV absorbents, and the like. The amounts used may be the previousamounts so long as the objects of the present invention are notimpaired.

EXAMPLES

The present invention will now be explained by Examples, but the presentinvention is of course not limited to these Examples.

(A) Standard Examples 1 to 10, Examples 1 to 40, and ComparativeExamples 1 to 11

The polysiloxanes 1 to 4 used for the formulations of the followingExamples etc. were synthesized by the following general methods:

Synthesis of Polysiloxane 1 (Polyisobutylene-Containing Polysiloxane)

50 g of H-siloxane (made by Wacker Chemicals) was added dropwise to 25 gof ethanol and 30 μl of a 2.5% chloroplatinic acid isopropyl alcoholsolution at 60° C. over 1 hour. After the dropwise addition was ended,the mixture was allowed to react at 70° C. for 2 hours. On the otherhand, 440 g of alkenyl terminated polyisobutylene (made by NipponPetrochemicals, high reactivity polyisobutene, molecular weight 3700)was dissolved in 220 of toluene, 60 g of silicone synthesized by theabove was added to this solution, then the mixture was allowed to reactat 80° C. for 4 hours. ¹ HNMR showed that the alkenyl groups of thepolyisobutylene disappeared and confirmed the presence of Si--CH₂ --CH.

Synthesis of Polysiloxane 2 (Polypropylene Glycol-ContainingPolysiloxane)

50 g of H-siloxane (made by Wacker Chemicals) was added dropwise to 25 gof ethanol and 30 μl of a 2.5% chloroplatinic acid isopropyl alcoholsolution at 60° C. over 1 hour. After the dropwise addition was ended,the mixture was allowed to react at 70° C. for 2 hours. Next, 260 g ofpropylene oxide-ethylene oxide copolymer arylbutyl ether (UnisafePKA-5017, made by Nippon Oil and Fats) (molecular weight 2500),PO/EO=50/50 (molar ratio)) was added and the mixture reacted at 80° C.for 4 hours. ¹ HNMR showed that the alkenyl groups of the polyetherdisappeared and confirmed the presence of Si--CH₂ --CH₂.

Synthesis of Polysiloxane 3(Polyisobutylene/Vinyltriethoxysilane-Containina Polysiloxane)

800 g of alkenyl terminated polyisobutylene (molecular weight 1250), 30g of vinyltriethoxysilane, 200 g of toluene, and 50 μl of a 2.5%chloroplatinic acid isopropyl solution were added to 50 g of H-siloxaneand allowed to react at 60° C. for 2 hours and 90° C. for 5 hours. ¹HNMR confirmed that the Si--H groups were reduced by over 90%. After theend of the reaction, the toluene and unreacted vinyltriethoxysilane weredistilled off.

Synthesis of Polysiloxane 4 (PolypropyleneGlycol/Vinyltriethoxysilane-Containing Polysiloxane)

1600 g of propylene oxide-ethylene oxide copolymer arylbutyl ether(Unisafe PKA-5017, made by Nippon Oil and Fats) (molecular weight 2500),30 g of vinyltriethoxysilane, 400 g of toluene, and 50 μl of a 2.5%chloroplatinic acid isopropyl solution were added to 50 g of H-siloxaneand allowed to react at 60° C. for 2 hours and 90° C. for 5 hours. ¹HNMR confirmed that the Si--H groups were reduced by over 90%. After theend of the reaction, the toluene and unreacted vinyltriethoxysilane weredistilled off.

For the rest of the formulating ingredients used for the formulations ofthe Standard Examples, Examples, and Comparative Examples, the followingcommercially available products were used.

The "vinyl amount" described here, however, is the fraction of thebutadiene component in the styrene-butadiene copolymer rubber. The "phr"is an abbreviation for per hundred rubber.

NR (natural rubber): SIR-20

SBR: Nipol 1502 (Nippon Zeon)

Emulsion polymerized styrene-butadiene copolymer rubber of a styreneamount of 24.5%, vinyl amount of 15.1%, weight average molecular weightof 430,000, and glass transition temperature of -52° C.

SBR: Nipol 9520 (Nippon Zeon)

37.5 phr oil extended emulsion polymerized styrene-butadiene copolymerrubber of a styrene amount of 37.9%, vinyl amount of 14.3%, weightaverage molecular weight of 840,000, and glass transition temperature of-32° C.

SBR: Nipol 1730 (Nippon Zeon)

20 phr oil extended emulsion polymerized styrene-butadiene copolymerrubber of a styrene amount of 25%, vinyl amount of 16%, weight averagemolecular weight of 650,000, and glass transition temperature of -50° C.

cis-BR: Nipol BR 1220

Weight average molecular weight of 450,000 and glass transitiontemperature of -102° C.

SBR: Nipol NS116 (Nippon Zeon)

Terminal modified/coupling treated solution polymerizationstyrene-butadiene copolymer rubber of a styrene amount of 20%, vinylamount of 65%, weight average molecular weight of 360,000, and glasstransition temperature of -30° C.

Carbon black: Seast KH (Tokai Carbon)

N₂ SA (m² /g)=92, DBP (ml/100 g)=117

Carbon black: Dia Black A (DIA I) (Mitsubishi Chemical)

N₂ SA (m² /g)=112, DBP (ml/100 g)=112

SAF carbon black: Seast 9M (Tokai Carbon)

N₂ SA (m² /g)=153, DBP (ml/100 g)=127

Silica: Nipsil AQ (Nippon Silica Industry)

Silane coupling.agent: Si69 (Degussa) (chemical name:bis-[3-(triethoxysilyl)-propyl]tetrasulfide)

Silanol condensation catalyst: Titanium chelate, Orgatics Tc-100 (madeby Matsumoto Seiyaku Kogyo)

Antioxidant 6C: N-phenyl-N'-(1,3-dimethylbutyl)-P-phenylene diamine

Vulcanization accelerator CZ: N-cyclohexyl-2-benzothiazyl sulfenamide

Vulcanization accelerator DPG: Diphenyl guanidine

Vulcanization accelerator NS: N-tert-butyl-2-benzothiazolyl sulfenamide

The silica- and carbon black-containing polysiloxane master batches 1 to9 used for the formulations of the following Examples were prepared bythe following general methods.

Predetermined amounts of silica and carbon black and predeterminedamounts of polysiloxane and other formulating ingredients (silanecoupling agents and silanol condensation catalysts) were mixed using a500 cc pressurized kneader type internal mixer for 5 to 10 minutes at aninternal mixer temperature of 100 to 120° C. to obtain master batches.

The formulations of the master batches were as follows:

Master batch 1: A silica-containing polysiloxane master batch comprising100 parts by weight of polysiloxane 1 and 50 parts by weight of silica(Nipsil AQ)

Master batch 2: A silica-containing polysiloxane master batch comprising100 parts by weight of polysiloxane 1, 50 parts by weight of silica(Nipsil AQ), and 5 parts by weight of a silane coupling agent

Master batch 3: A silica-containing polysiloxane master batch comprising100 parts by weight of polysiloxane 1, 50 parts by weight of silica(Nipsil AQ), 5 parts by weight of a silane coupling agent, and 1 part byweight of a silanol condensation catalyst (TPT100)

Master batch 4: A silica-containing polysiloxane master batch comprising100 parts by weight of Yt polysiloxane 1 and 100 parts by weight ofsilica (Nipsil AQ)

Master batch 5: A carbon black-containing polysiloxane master batchcomprising 100 parts by weight of polysiloxane 1 and 50 parts by weightof carbon black (DIA-1)

Master batch 6: A silica- and carbon black-containing polysiloxanemaster batch comprising 100 parts by weight of polysiloxane 1, 30 partsby weight of silica (Nipsil AQ), and 30 parts by weight of carbon black(DIA-1)

Master batch 7: A silica-containing polysiloxane master batch comprising100 parts by weight of polysiloxane 2 and 50 parts by weight of silica(Nipsil AQ)

Master batch 8: A silica-containing polysiloxane master batch comprising100 parts by weight of polysiloxane 2, 50 parts by weight of silica(Nipsil AQ), and 5 parts by weight of silane coupling agent

Master batch 9: A carbon black-containing polysiloxane master batchcomprising 100 parts by weight of polysiloxane 1 and 50 parts by weightof carbon black (SAF grade carbon black)

Preparation of Samples

The ingredients except for the vulcanization accelerator and sulfur werekneaded in a 1.6 liter internal mixer for 3 to 5 minutes and weredischarged when they reached 165±5° C. The vulcanization accelerator andsulfur were kneaded with the master batch by an 8-inch open roll toobtain a rubber composition. The unvulcanized physical property, thatis, the "Mooney viscosity", of the obtained rubber composition was thenmeasured.

Next, the composition was vulcanized by pressing in a 15×15×0.2 cm moldat 160° C. for 20 minutes to prepare the desired test piece (rubbersheet) which was then evaluated as to its vulcanized physicalproperties, that is, "amount of extraction of solvent", "300% modulus","JIS hardness: room temperature and -20° C.", "JIS hardness: measured atroom temperature after heating and aging in air", "tanδ: 0° C. and 60°C.", "ice skid resistance and wet skid resistance", and "abrasionresistance".

The test methods for the unvulcanized physical properties and vulcanizedphysical properties of the compositions obtained in the Examples were asfollows:

Amount of Extraction of Solvent of Vulcanized Rubber

0.5 g of rubber was Soxhlet extracted for 8 hours using n-hexane as anextraction solvent.

Unvulcanized Physical Properties

1) Mooney viscosity: Measured at 100° C. based on JIS K 6300.

Vulcanized Physical Properties

1) 300% modulus: Measured in accordance with JIS K 6251 (dumbbell No. 3)

2) JIS hardness (room temperature and -20° C.): Measured in accordancewith JIS K 6253

Further, the test of aging by heating in air was performed in accordancewith JIS K 6250 and measurement conducted at 100° C. for 48 hours.

3) tanδ (0° C. and 60° C.): Viscoelasticity measured using a Toyo SeikiSeisakusho Rheorograph Solid at an initial strain of 10%, a dynamicstrain of 2%, and a frequency of 20 Hz (sample width: 5 mm).

4) Ice skid resistance and wet skid resistance: Measured using a BritishPortable Skid Tester under conditions of an icy road surface(temperature: -3° C.) and a wet road surface (temperature: roomtemperature) and indexed to the Standard Example as 100. The larger thevalue, the better the skid resistance.

5) Abrasion resistance

The amount of abrasion loss was measured using a Lanbourn abrasiontester (made by Iwamoto Seisakusho) under conditions of a temperature of20° C. and a slip rate of 50% and was indexed to the Standard Example as100. The larger the value, the better the abrasion resistance.

Standard Examples 1 to 2, Examples 1 to 10, and Comparative Examples 1to 2

These Examples show the results of evaluation for rubber compositionscomprising NR rubber compositions in which the above polysiloxane 1 or 2is formulated. The formulations and results of the Examples are shown inthe following Table I.

                                      TABLE I                                     __________________________________________________________________________                    Stand.  Comp.                                                                             Stand.      Comp.                                    Ex. 1 Ex. 1 Ex. 1 Ex. 2 Ex. 2 Ex. 3 Ex. 2                                  __________________________________________________________________________      NR (SIR-20) 100.0 100.0 100.0 100.0 100.0 100.0 100.0                         SBR (Nipol 1502)                                                              Carbon black (Seast KH) 50.0 50.0 50.0 30.0 30.0 30.0 30.0                    Silica (Nipsil AQ)    20.0 20.0 20.0 20.0                                     Silane coupling agent (Si69)    2.0  2.0 2.0                                  Activant (diethylene glycol)    2.0 2.0 2.0 2.0                               Silanol condensation catalyst                                                 Polysiloxane 1  20.0   20.0 20.0                                              Polysiloxane 2                                                                Zinc White No. 3 3.0 3.0 3.0 3.0 3.0 3.0 3.0                                  Industrial stearic acid 1.0 1.0 1.0 1.0 1.0 1.0 1.0                           Antioxidant 6C 1.0 1.0 1.0 1.0 1.0 1.0 1.0                                    Aromatic process oil   20    20. 0                                            Oil treated powdered sulfur 1.7 1.7 1.7 1.7 1.7 1.7 1.7                       Vulcanization accelerator CZ 1.0 1.0 1.0 1.0 1.0 1.0 1.0                      Vulcanization accelerator DPG    0.5 0.5 0.5 0.5                              Amount of solvent extracted of 5.8 8.7 25.7 6.2 6.3 6.1 25.5                  vulcanized rubber (/100 parts rubber)                                         [Unvulcanized physical properties]                                            Mooney viscosity 101 48 58 125 63 61 66                                       [Vulcanized physical properties]                                              300% modulus (MPa) 14.1 9.9 10.3 12.1 9.2 10.1 9.3                            JIS hardness (room temp.) 62 57 58 63 58 59 58                                JIS hardness (-20° C.) 69 61 62 67 59 60 61                            tanδ (0° C.) 0.25 0.31 0.30 0.21 0.26 0.27 0.25                  tanδ (60° C.) 0.15 0.13 0.19 0.13 0.11 0.10 0.16                 Ice skid resistance (-3° C.) 100 120 118 112 131 133 129                                                      Abrasion resistance 100 70 60 73                                             61 65 41                              __________________________________________________________________________                    Ex. 4                                                                             Ex. 5                                                                             Ex. 6                                                                             Ex. 7                                                                             Ex. 8                                                                             Ex. 9                                                                             Ex. 10                                __________________________________________________________________________      NR (SIR-20) 100.0 100.0 100.0 100.0 100.0 100.0 100.0                         SBR (Nipol 1502)                                                              Carbon black (Seast KH) 50.0 30.0 30.0 30.0 30.0 30.0 30.0                    Silica (Nipsil AQ)  20.0 20.0 20.0 20.0 20.0 20.0                             Silane coupling agent (Si69)  2.0 2.0 2.0 2.0 2.0 2.0                         Activant (diethylene glycol)  2.0 2.0 2.0 2.0 2.0 2.0                         Silanol condensation catalyst  1.0 1.0                                        Polysiloxane 1  20.0  10.0 30.0                                               Polysiloxane 2 20.0  20.0   10.0 50.0                                         Zinc White No. 3 3.0 3.0 3.0 3.0 3.0 3.0 3.0                                  Industrial stearic acid 1.0 1.0 1.0 1.0 1.0 1.0 1.0                           Antioxidant 6C 1.0 1.0 1.0 1.0 1.0 1.0 1.0                                    Aromatic process oil                                                          Oil treated powdered sulfur 1.7 1.7 1.7 1.7 1.7 1.7 1.7                       Vulcanization accelerator CZ 1.0 1.0 1.0 1.0 1.0 1.0 1.0                      Vulcanization accelerator DPG  0.5 0.5 0.5 0.5 0.5 0.5                        Amount of solvent extracted of 5.6 6.2 6.1 5.9 6.5 6.0 7.0                    vulcanized rubber (/100 parts rubber)                                         [Unvulcanized physical properties]                                            Mooney viscosity 49.1 51.1 52.1 78.2 49.1 77.5 36.9                           [Vulcanized physical properties]                                              300% modulus (MPa) 9.9 9.2 9.3 12.1 7.9 11.8 6.3                              JIS hardness (room temp.) 57 58 57 61 56 60 52                                JIS hardness (-20° C.) 61 61 60 64 58 63 56                            tanδ (0° C.) 0.23 0.26 0.21 0.25 0.28 0.21 0.17                  tanδ (60° C.) 0.13 0.11 0.10 0.12 0.10 0.12 0.09                 Ice skid resistance (-3° C.) 118 128 132 111 138 108 142                                                      Abrasion resistance 71 61 68 83                                              51 88 51                              __________________________________________________________________________

From the results of Table I, the following is understood.

In the compositions of Examples 1 to 10 comprising the rubbercompositions of the Standard Examples 1 and 2 in which predeterminedamounts of polysiloxane 1 or 2 is formulated, while the degree ofmigration is kept low (acetone extracted weight is small), theprocessability when unvulcanized is remarkably increased (Mooneyviscosity falls). Further, judging from the vulcanized physicalproperties, it was learned that the compositions are superior in termsof the temperature dependency of the hardness, the tans balance, and theperformance on ice. As opposed to this, in Comparative Examples 1 and 2where polysiloxane 1 or 2 was not added, but an aromatic process oil(softening agent) was added and the processability when unvulcanized wasincreased, the abrasion resistance declined and the migration remarkablyincreased. Further, as shown in Examples 5 to 10, when the amount of thepolysiloxane 1 or 2 was changed, it was learned that an increase of theamount formulated leads to a major improvement in the processability andperformance on ice while at least keeping the migration small.

Standard Examples 3 to 4, Examples 11 to 13, and Comparative Examples 3to 4

These Examples show the results of evaluation for rubber compositionscomprising SBR rubber compositions in which the above polysiloxane 1 or2 is formulated. The formulations and results of the Examples are shownin the following Table II.

From the results of Table II, the following is understood.

                                      TABLE II                                    __________________________________________________________________________                    Stand.  Comp.                                                                             Stand.      Comp.                                   Ex. 3 Ex. 11 Ex. 3 Ex. 4 Ex. 12 Ex. 13 Ex. 4                                __________________________________________________________________________    NR (SIR-20)                                                                     SBR (Nipol 1502) 100.0  100.0  100.0  100.0  100.0  100.0  100.0                                                     Carbon black (Seast KH) 50.0                                                 50.0  50.0  30.0  30.0  30.0                                                  30.0                                    Silica (Nipsil AQ)    20.0  20.0  20.0  20.0                                  Silane coupling agent (Si69)    2.0 2.0 2.0 2.0                               Activant (diethylene glycol)    2.0 2.0 2.0 2.0                               Silanol condensation catalyst                                                 Polysiloxane 1  20.0    20.0                                                  Polysiloxane 2      20.0                                                      Zinc White No. 3 3.0 3.0 3.0 3.0 3.0 3.0 3.0                                  Industrial stearic acid 1.0 1.0 1.0 1.0 1.0 1.0 1.0                           Antioxidant 6C 1.0 1.0 1.0 1.0 1.0 1.0 1.0                                    Aromatic process oil   20.0     20.0                                          Oil treated powdered sulfur 1.7 1.7 1.7 1.7 1.7 1.7 1.7                       Vulcanization accelerator CZ 1.0 1.0 1.0 1.0 1.0 1.0 1.0                      Vulcanization accelerator DPG    0.5 0.5 0.5 0.5                              Amount of solvent extracted of 9.3 10.1  29.5  9.5 9.5 9.6 29.6                                                      vulcanized rubber (/100 parts                                                rubber)                                 [Unvulcanized physical properties]                                            Mooney viscosity 83.2  43.2  45.3  98.1  51.1  50.2  49.3                     [Vulcanized physical properties]                                              300% modulus (MPa) 18.2  9.5 11.4  11.3  8.2 8.3 8.1                          JIS hardness (room temp.)  69  63  61  70  64  63  63                         JIS hardness (-20° C.)  79  72  73  79  72  71  75                     tanδ (0° C.)  0.30  0.36  0.35  0.27  0.32  0.24  0.31                                                  tanδ (60° C.)  0.21                                              0.16  0.26  0.17  0.16  0.15                                                 0.21                                    Ice skid resistance (-3° C.) 100 118 117 109 132 136 131                                                      Wet skid resistance (room temp.)                                             100 110 108  92 102  92 102                                                    Abrasion resistance 100  75  73                                              81  63  65  60                        __________________________________________________________________________

In the compositions of Examples 11 to 13 comprised of the rubbercompositions of Standard Examples 3 and 4 in which predetermined amountsof the polysiloxane 1 or 2 is formulated, it was learned that theprocessability when unvulcanized can be remarkably increased whilekeeping the degree of migration low and the temperature dependency ofhardness, the tanS balance, the performance on ice, and the wet grip aresuperior. As opposed to this, in Comparative Examples 3 and 4 wherepolysiloxane 1 or 2 is not added, but an aromatic process oil is addedand the processability when unvulcanized is increased, the abrasionresistance deteriorates and the migration remarkably increases.

Standard Examples 5 to 6, Examples 14 to 17 and Comparative Examples 5to 8

These Examples show the results of evaluation for rubber compositionscomprising NR+cisBR rubber compositions in which the above polysiloxane1 or 2 is formulated. The formulations and results of the Examples areshown in the following Table III.

                                      TABLE III                                   __________________________________________________________________________                    Stand   Comp.                                                                             Comp.                                                                             Stand.  Comp.       Comp.                       Ex. 5 Ex. 4 Ex. 5 Ex. 6 Ex. 6 Ex. 15 Ex. 7 Ex. 16 Ex. 17 Ex. 8              __________________________________________________________________________    NR (SIR-20)     60.0                                                                              60.0                                                                              60.0                                                                              60.0                                                                              60.0                                                                              60.0                                                                              60.0                                                                              60.0                                                                              60.0                                                                              60.0                        cisBR (Nipol BR1220) 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0                                                           Carbon black (DIA-1)                                                         50.0 50.0 50.0 50.0                                                           30.0 30.0 30.0 50.0                                                           30.0 30.0                   Silica (Nipsil AQ)     20.0 20.0 20.0  20.0 20.0                              Silane coupling agent (Si69)     2.0 2.0 2.0  2.0 2.0                         Activant (diethylene glycol)     2.0 2.0 2.0  2.0 2.0                         Silanol condensation catalyst                                                 Polysiloxane 1  20.0    20.0                                                  Polysiloxane 2        20.0 20.0                                               Zinc White No. 3 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0                      Industrial stearic acid 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0                                                                  Antioxidant 6C 1.0                                                           1.0 1.0 1.0 1.0 1.0                                                           1.0 1.0 1.0 1.0                                                                Polyisobutene                                                                (Vistanex) *1                                                                  20.0                       Aromatic process oil 10.0 10.0 30.0 10.0 10.0 10.0 10.0 30.0 10.0 10.0                                                           Low mol. weight                                                              butadiene rubber*2                                                            20.0                        Oil treated powdered sulfur 1.7 1.7 1.7 1.7 1.7 1.7 1.7 1.7 1.7 1.7                                                              Vulcanization                                                                accelerator NS 1.0                                                            1.0 1.0 1.0 1.0 1.0                                                           1.0 1.0 1.0 1.0                                                                Vulcanization                                                                accelerator DPG                                                               0.5 0.5 0.5  0.5 0.5                                                           Amount of solvent                                                            extracted of 15.0                                                             15.9 35.7 24.9 15.6                                                           16.3 35.5 15.9 16.3                                                           28.2                        vulcanized rubber (/100 parts rubber)                                         [Unvulcanized physical properties]                                            Mooney viscosity 69 45 49 47 76 50 47 45 50 66                                [Vulcanized physical properties]                                              300% modulus (MPa) 7.9 5.3 5.4 5.1 7.0 5.1 5.3 5.3 5.1 7.0                    JIS hardness (room temp.) 60 48 49 50 58 50 49 49 51 54                       JIS hardness (-20° C.) 71 55 60 59 68 57 59 56 58 63                   JIS hardness (measured at room 65 50 51 57 61 53 53 52 54 57                  temp. after aging by heating in air)                                          tanδ (0° C.) 0.27 0.31 0.30 0.26 0.24 0.30 0.27 0.27 0.23                                                          0.26                        tanδ (60° C.) 0.20 0.18 0.22 0.19 0.17 0.15 0.20 0.20 0.14                                                         0.20                        Ice skid resistance (-3° C.) 100 116 116 110 107 119 118 117 121                                                         109                         Abrasion resistance 100 82 79 81 88 68 42 81 70 59                          __________________________________________________________________________     (*1: Shell Chemicals Vistanex L140, *2: Nippon Petrochemicals, liquid         polybutadiene B3000)                                                     

From the results of Table III, the following was learned.

In the compositions of Examples 14 to 17 comprised of the rubbercompositions of Standard Examples 5 and 6 in which predetermined amountsof polysiloxane 1 or 2 is formulated (in this examples, 10 parts byweight of a softening agent, that is, an aromatic process oil, isformulated), it was learned that the processability when unvulcanized isincreased while the degree of migration is kept low and the temperaturedependency of hardness, the tanδ balance, and the performance on ice areimproved. As opposed to this, however, in Comparative Examples 5 to 8where polysiloxane 1 or 2 is not added, but the amount of the softeningagent (aromatic process oil or this and lower molecular weight butadieneor polyisobutene used together) formulated is increased (softening agentincreased from 10 parts by weight to 30 parts by weight), the abrasionresistance deteriorates much more and the migration is remarkablyincreased. The changes in hardness after aging by heating in air werealso lower compared with the case of a low molecular weight butadiene.Further, compared with Examples 16 and 17, it is learned that if apredetermined amount of polysiloxane 2 is formulated in a rubbercomposition, even if silica is used for part of the filler,substantially the same performance is obtained as with formulating afiller comprised solely of carbon black (however, only the performanceon ice improved).

Standard Examples 7 to 8, Examples 18 to 22, and Comparative Examples 9to 11

These Examples show the results of evaluation for rubber compositionscomprising SBR rubber compositions of different amounts of oil extensionin which the above polysiloxane 1 or 2 is formulated. The formulationsand results of the Examples are shown in the following Table IV.

                                      TABLE IV                                    __________________________________________________________________________                    Stand.  Comp.                                                                             Stand.      Comp.                                                                             Comp.                               Ex. 7 Ex. 18 Ex. 9 Ex. 8 Ex. 19 Ex. 20 Ex. 10 Ex. 11 Ex. 21 Ex.             __________________________________________________________________________                                                        22                        SBR/Nipol 9520  96.25                                                                             96.25                                                                             96.25                                                                             96.25                                                                             96.25                                                                             96.25                                                                             96.25                                                                             96.25                                                                             96.25                                                                             96.25                       SBR/Nipol 1730 36.00 36.00 36.00 36.00 36.00 36.00 36.00 36.00 36.00                                                            36.00                       SAF carbon black 80.0 80.0 80.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0                                                               Silica (Nipsil AQ)                                                            20.0 20.0 20.0 20.0                                                          20.0 20.0 20.0                                                                 Silane coupling                                                              agent (Si69)    2.0                                                           2.0 2.0 2.0 2.0 2.0                                                           2.0                         Activant (diethylene glycol)    2.0 2.0 2.0 2.0 2.0 2.0 2.0                   Silanol condensation catalyst                                                 Polysiloxane 1  20.0   20.0                                                   Polysiloxane 2      20.0                                                      Polysiloxane 3         20.0                                                   Polysiloxane 4          20.0                                                  Zinc White No. 3 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0                      Industrial stearic acid 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0                                                                  Antioxidant 6C 2.0                                                           2.0 2.0 2.0 2.0 2.0                                                           2.0 2.0 2.0 2.0                                                                Polyisobutene                                                                (Vistanex) *1                                                                  Aromatic process oil                                                           20.0    20.0 20.0                                                            Oil treated powdered                                                         sulfur 2.0 2.0 2.0                                                            2.0 2.0 2.0 2.0 2.0                                                           2.0 2.0                     Vulcanization accelerator CZ 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0                                                             Amount of solvent                                                            extracted of 40.1                                                             41.5 61.2 41.6 41.7                                                           42.1 62.7 57.1 40.1                                                           40.7                        vulcanized rubber (/100 parts rubber)                                         [Unvulcanized physical properties]                                            Mooney viscosity 75 66 65 81 71 72 70 73 71 71                                [Vulcanized physical properties]                                              300% modulus (MPa) 7.9 8.1 8.3 11.2 8.1 7.7 7.9 8.5 7.8 8.0                   JIS hardness (room temp.) 71 64 63 70 64 65 64 66 64 65                       JIS hardness (-20° C.) 94 88 89 93 86 84 87 88 85 84                   tanδ (0° C.) 0.74 0.77 0.77 0.73 0.75 0.70 0.76 0.74 0.74                                                          0.71                        tanδ (60° C.) 0.33 0.31 0.31 0.30 0.28 0.27 0.33 0.35 0.25                                                         0.26                        Wet skid resistance (room temp.) 100 105 104 103 107 102 107 105 105                                                            104                         Abrasion resistance 100 88 83 83 75 77 55 49 88 87                          __________________________________________________________________________     (*1: Shell chemicals Vistanex L140)                                      

From the results of Table IV, the following was learned.

In the compositions of Examples 18 to 22 comprising the rubbercompositions of Standard Examples 7 and 8 in which predetermined amountsof polysiloxanes 1 to 4 are formulated (these further including processoil through oil extension), it was learned that the processability whenunvulcanized is remarkably increased while maintaining the degree ofmigration and the temperature dependency of the hardness and performanceon ice are good. As opposed to this, in Comparative Examples 9 to 11where the polysiloxane 1 or 2 is not added, but aromatic process oil isadded, the processability when unvulcanized is increased, the abrasionresistance remarkably deteriorates and the migration considerablyincreases.

Examples 23 to 27

These Examples relate to polysiloxane master batches containing silicaand carbon black and show the results of evaluation for rubbercompositions comprising NR+cisBR and different oil extension amount ofSBR rubber compositions. The formulations and results of the Examplesare shown in the following Table V.

                                      TABLE V                                     __________________________________________________________________________                    Ex. 23                                                                            Ex. 24                                                                            Ex. 25                                                                            Ex. 26                                                                            Ex. 27                                                                            Ex. 28                                                                            Ex. 29                                                                            Ex. 30                            __________________________________________________________________________      NR (SIR-20) 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0                           cis-Br (Nipol Br1220) 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0                 SBR/Nipol 9520                                                                SBR/Nipol 1730                                                                Carbon black (DIA-1) 30.0 30.0 30.0 30.0 40.0 24.0 30.0 30.0                  Carbon black (SAF)                                                            Silica (Nipsil AQ) 10.0 10.0 10.0   14.0 10.0 10.0                            Silane coupling agent (Si69) 2.0 1.0 1.0 1.0   2.0 1.0                        Activant (diethylene glycol) 2.0 2.0 2.0 2.0   2.0 2.0                        Silanol condensation catalyst                                                 Master batch 1 30.0                                                           Master batch 2  31.0                                                          Master batch 3   31.2                                                         Master batch 4    40.0                                                        Master batch 5     30.0                                                       Master batch 6      32.0                                                      Master batch 7       30.0                                                     Master batch 8        31.0                                                    Zinc White No. 3 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0                              Industrial stearic acid 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0                       Antioxidant 6C 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0                                Polyisobutene (Vistanex)                                                      Aromatic process oil 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0                  Low mol. weight butadiene rubber                                              Oil treated powdered sulfur                                                   Vul. accelerator NS 1.7 1.7 1.7 1.7 1.7 1.7 1.7 1.7                           Vul. accelerator CZ 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0                           Vul. accelerator DPG                                                           0.5 0.5 0.5 0.5  0.5 0.5 0.5                                                 Amount of solvent extracted of 15.7 15.4 15.8 16.1 16.0 15.9 16.2 16.2                                                   vulcanized rubber (/100                                                      parts rubber)                       [Unvulcanized physical properties]                                            Mooney viscosity 50 51 51 52 48 50 46 47                                      [Vulcanized physical properties]                                              300% modulus (MPa) 5.2 5.4 5.5 5.4 5.4 5.1 5.0 5.1                            JIS hardness (room temp.) 49 49 50 50 49 51 51 51                             JIS hardness (-20° C.) 56 57 57 57 55 57 56 56                         JIS hardness (measured at room 52 53 52 52 51 52 53 54                        temp. after aging by heating in air)                                          tanδ (0° C.) 0.31 0.31 0.30 0.31 0.31 0.30 0.23 0.22                                                        tanδ (60° C.)                                                   0.15 0.14 0.13 0.13 0.17 0.15                                                 0.14 0.12                           Ice skid resistance (-3° C.) 116 115 114 114 115 116 122 124                                                      Wet skid resistance (room                                                    temp.)                              Abrasion resistance 75 80 55 85 85 77 73 77                                 __________________________________________________________________________                        Ex. 31                                                                            Ex. 32                                                                            Ex. 33                                                                            Ex. 34                                                                            Ex. 35                                                                            Ex. 36                                                                            Ex. 37                            __________________________________________________________________________      NR (SIR-20)                                                                   cis-Br (Nipol Br1220)                                                         SBR/Nipol 9520 96.25 96.25 96.25 96.25 96.25 96.25 96.25                      SBR/Nipol 1730 36.00 36.00 36.00 36.00 36.00 36.00 36.00                      Carbon black (DIA-1)                                                          Carbon black (SAF) 60.0 60.0 60.0 60.0 60.0 60.0 60.0                         Silica (Nipsil AQ) 10.0 10.0 10.0 10.0 10.0 10.0 10.0                         Silane coupling agent (Si69) 2.0 1.0 1.0 1.0 1.0 1.0 1.0                      Activant (diethylene glycol) 2.0 2.0 2.0 2.0 2.0 2.0 2.0                      Silanol condensation catalyst                                                 Master batch 1 30.0                                                           Master batch 2  31.0                                                          Master batch 3   31.2                                                         Master batch 4    40.0                                                        Master batch 5                                                                Master batch 6                                                                Master batch 7      30.0                                                      Master batch 8       31.0                                                     Zinc White No. 3 3.0 3.0 3.0 3.0 3.0 3.0 3.0                                  Industrial stearic acid 2.0 2.0 2.0 2.0 2.0 2.0 2.0                           Antioxidant 6C 2.0 2.0 2.0 2.0 2.0 2.0 2.0                                    Polyisobutene (Vistanex)                                                      Aromatic process oil                                                          Low mol. weight butadiene rubber                                              Oil treated powdered sulfur                                                   Vul. accelerator NS 2.0 2.0 2.0 2.0 2.0 2.0 2.0                               Vul. accelerator CZ                                                           Vul. accelerator DPG 2.0 2.0 2.0 2.0 2.0 2.0 2.0                              Amount of solvent extracted of 41.6 41.2 40.0 41.0 42.0 41.1 40.6                                                        vulcanized rubber (/100                                                      parts rubber)                       [Unvulcanized physical properties]                                            Mooney viscosity 73 73 72 72 67 73 74                                         [Vulcanized physical properties]                                              300% modulus (MPa) 8.2 8.4 8.5 8.5 8.3 7.7 7.9                                JIS hardness (room temp.) 65 65 66 66 65 66 67                                JIS hardness (-20° C.) 86 85 85 85 87 84 83                            JIS hardness (measured at room                                                temp. after aging by heating in air)                                          tanδ (0° C.) 0.75 0.75 0.74 0.76 0.75 0.69 0.70                  tanδ (60° C.) 0.27 0.26 0.25 0.25 0.31 0.26 0.25                 Ice skid resistance (-3° C.)                                           Wet skid resistance (room temp.) 108 109 107 108 106 103 104                  Abrasion resistance 79 83 85 85 92 83 87                                    __________________________________________________________________________     (Note: The ice skid resistance and abrasion resistance of Examples 23 to      30 are shown as indexes against Standard Example 5 as 100.)                   (Note: The wet skid resistance and abrasion resistance of Examples 31 to      37 are shown as indexes against Standard Example 7 as 100.)              

From the results of Table V, the following was learned.

It was learned that with the same formulations, the abrasion resistanceis improved and other properties do not decline by making master batchesof the polysiloxanes. Further, if a silane coupling agent and silanolcondensation catalyst is formulated in at the master batch stage, theabrasion resistance is further improved and the reinforcing ability isincreased.

Standard Examples 9 to 10 and Examples 38 to 40

These Examples show the results of evaluation for rubber compositions ofNR+SBR +silica formulations. The formulations of the Examples and theresults are shown in Table VI.

                  TABLE VI                                                        ______________________________________                                                    Stan-        Stan-                                                  dard  dard                                                                    Ex. 9 Ex. 38 Ex. 10 Ex. 39 Ex. 40                                           ______________________________________                                        NR (SIR-20)   50.0   50.0    50.0  50.0  50.0                                   SBR (Nipol NS116) 50.0  50.0  50.0  50.0  50.0                                Silica (Nipsil AQ) 50.0  50.0  50.0  50.0  50.0                               Silane coupling agent   2.5 2.5 2.5                                           (Si69)                                                                        Activant (diethylene glycol) 2.5 2.5 2.5 2.5 2.5                              Polysiloxane  5.0  5.0 5.0                                                    Zinc White No. 3 3.0 3.0 3.0 3.0 3.0                                          Industrial stearic acid 1.0 1.0 1.0 1.0 1.0                                   Antioxidant 6C 1.0 1.0 1.0 1.0 1.0                                            Oil treated powdered sulfur 1.7 1.7 1.7 1.7 1.7                               Vulcanization accelerator 0.5 0.5 0.5 0.5 0.5                                 DPG                                                                           Vulcanization accelerator 1.0 1.0 1.0 1.0 1.0                                 CZ                                                                            Amount of solvent 5.2 5.7 5.6 5.9 6.0                                         extracted of vulcanized                                                       rubber (/100 parts rubber)                                                    [Unvulcanized physical                                                        properties]                                                                   Mooney viscosity 148 128 111  92  74                                          [Vulcanized physical                                                          properties]                                                                   300% modulus (MPa) 4.0 3.3 9.3 9.0 7.1                                        JIS hardness (room temp.)  69  64  68  61  60                                 JIS hardness (-20° C.)  87  81  83  75  73                             tanδ (0° C.)  0.45  0.49  0.46  0.49  0.54                       tanδ (60° C.)  0.11  0.12  0.12  0.12  0.13                      Wet skid resistance 100 103 101 103 106                                       (room temp.)                                                                  Abrasion resistance 100 127 135 181 154                                     ______________________________________                                    

The following was learned from the results of Table VI.

In Examples 38 to 40, comprised of Standard Examples 9 and 10 in whichpredetermined amounts of the polysiloxane 1 were formulated, it islearned that the processability when unvulcanized was remarkablyincreased while maintaining the degree of migration and the temperaturedependency of the hardness was reduced. Further, in silica formulations,it is learned that the addition of polysiloxane gives a plasticizingeffect and improves the abrasion resistance. Further, the lowtemperature side tan5 was improved without raising the high temperatureside tan6, and the wet skid resistance was improved.

(B) Regarding Examples 41 to 51 and Comparative Examples 12 to 13

The plasticizers F to M used for the formulations in the followingExamples were those of the above chemical formulas. Further, thefollowing commercially available products were used for the rest of theformulating ingredients:

Silica: Nipsil AQ (Nippon Silica Industry)

Talc: (Kanto Kagaku Chemicals)

Calcium carbonate: Calfine 200 (Maruo Calcium)

Carbon black: Seast KH (Tokai Carbon)

NR: SIR-20

SBR: Nipol 1502 (Nippon Zeon)

Vulcanization accelerator CZ: N-cyclohexyl-2-benzothiazyl sulfenamide

Urethane: Coronet 4090 (Nippon Polyurethane Industry), methylene biso-chloroaniline (curing agent) (100:12.7)

The test method for the acetone extracted weight obtained in theexamples was as follows:

Acetone Extracted Weight

5 g of each sample was weighed and Soxhlet extracted by acetone for 8hours, then the value was converted to a percentage of the total weight.

Examples 41 to 51 and Comparative Examples 12 to 13

These Examples show the results of evaluation for rubber compositionsand urethane resin compositions comprised of NR+SBR rubber compositionsand urethane resins in which the above plasticizers F to M areformulated.

Regarding the ingredients of the formulations (parts by weight) shown inTable VII, in Examples 41 and 42 and Comparative Example 12, thereactive plasticizer was stirred and mixed with a predetermined amountof filler at room temperature for 5 minutes, while in Examples 44 to 51,calcium carbonate and reactive plasticizer were added to the urethaneand the mixture was kneaded by a universal stirring machine for 5minutes, then the curing agent was added to obtain the compositions. InExamples 43 and Comparative Example 13, however, the ingredients exceptfor the sulfur and vulcanization accelerator were mixed in a 1.8 literinternal mixer for 3 to 5 minutes. When reaching 165±5° C., the mixturewas discharged. The sulfur and vulcanization accelerator were kneadedwith the master batch by an 8-inch open roll to obtain the rubbercomposition.

The thus obtained rubber composition or resin composition was processedunder the conditions shown in Table VII. The acetone extracted weightwas found for the obtained compositions. The results are shown in TableVII.

                                      TABLE VII                                   __________________________________________________________________________                                                           Comp.                                                                             Comp.                Ex. 41 Ex. 42 Ex. 43 Ex. 44 Ex. 45 Ex. 46 Ex. 47 Ex. 48 Ex. 49 Ex. 50                                                                  Ex. 51 Ex. 12                                                                 Ex. 13             __________________________________________________________________________    Silica   100 --  --   --  --  --  --   --  --  --  --  100 --                   Talc -- 100 -- -- -- -- -- -- -- -- -- -- --                                  Calcium carbonate -- -- -- 50 50 50 50 50 50 50 50 -- --                      Carbon black -- -- 50 -- -- -- -- -- -- -- -- -- 50                           NR -- -- 50 -- -- -- -- -- -- -- -- -- 50                                     SBR -- -- 50 -- -- -- -- -- -- -- -- -- 50                                    Sulfur -- -- 1.7 -- -- -- -- -- -- -- -- -- 1.7                               Vul. accelerator CZ -- -- 1 -- -- -- -- -- -- -- -- -- 1                      Urethane -- -- -- 100 100 100 100 100 100 100 100 -- --                       Plasticizer F -- -- -- -- 20 -- -- -- -- -- -- -- --                          Plasticizer G 20 20 20 20 -- -- -- -- -- -- -- -- --                          Plasticizer H -- -- -- -- -- 20 -- -- -- -- -- -- --                          Plasticizer I -- -- -- -- -- -- 20 -- -- -- -- -- --                          Plasticizer J -- -- -- -- -- -- -- 20 -- -- -- -- --                          Plasticizer K -- -- -- -- -- -- -- -- 20 -- -- -- --                          Plasticizer L -- -- -- -- -- -- -- -- -- 20 -- -- --                          Plasticizer M -- -- -- -- -- -- -- -- -- -- 20 -- --                          Butyl oleate -- -- -- -- -- -- -- -- -- -- -- 20 20                           Treatment                                                                     conditions                                                                    Temp. (° C.) 160 160 160 120 120 120 120 120 120 120 120 120 120       Time 20 min 20 min 20 min 5 hr 5 hr 5 hr 5 hr 5 hr 5 hr 5 hr 5 hr 20                                                                   min 20 min                                                                     Acetone                                                                      extracted 0.8                                                                 1.3 3.4 1.5                                                                   3.1 1.8 0.6                                                                   2.3 1.7 1.8                                                                   1.8 18.3 19.2                                                                  weight            __________________________________________________________________________                                                               (g)            

As is made clear by the results of Table VII, the reactive plasticizersF to M of the present invention reacts with silica, talc, carbon black,and calcium carbonate or self reacts, therefore the acetone extractedweight is extremely small. Compared with this, in Comparative Examples12 and 13, no reaction occurs and the extraction of acetone is easy.

INDUSTRIAL APPLICABILITY

As explained above, according to the present invention, by formulatingthe modified polysiloxane of the present invention in a rubbercomposition, in particular a tire tread rubber composition of a specificformulation, it is possible to improve the processability whenunvulcanized, while maintaining no migration and obtain a rubbercomposition giving a cured product which is soft even at lowtemperatures, superior in performance on ice and wet grip, and superiorin the tans balance and abrasion resistance.

Further, the reactive plasticizer of the present invention, which is anester-based plasticizer and, therefore can be used over a wide range ofapplications such as rubber and resins and, in particular in a silicaformulation, is non-bleeding. Further, it reacts with other fillers(carbon black and calcium carbonate) to achieve a non-bleedingcharacteristic.

What is claimed is:
 1. A polysiloxane having a siloxane structure of the following formulas (1) and (2): ##STR17## wherein R¹ is a C₁ to C₆ alkyl group or C₁ to C₂₁ acyl group, a is 1 to 200, b is 2 to 200, t is 2 or 3, and r is 1 to
 100. 2. A rubber composition characterized by comprising 100 parts by weight of rubber and 1 to 50 parts by weight of a polysiloxane having a siloxane structure of the following formulas (1) and (2): ##STR18## wherein R¹ is a C₁ to C₆ alkyl group or C₁ to C₂₁ acyl group, a is 1 to 200, b is 1 to 200, t is 2 or 3, and r is 1 to 100, formulated therein.
 3. A rubber composition as set forth in claim 2, comprising silica.
 4. A tire tread rubber composition comprising 100 parts by weight of at least one rubber selected from the group consisting of natural rubber, polybutadiene rubber, styrene-butadiene copolymer rubber, and polyisoprene rubber and 45 to 80 parts by weight of at least one filler selected from the group consisting of carbon blacks having a specific surface area by nitrogen adsorption (N₂ SA) of 50 to 170 m² /g and a dibutyl phthalate oil absorption (DBP) of 60 to 140 ml/100 g or other fillers, 5 to 50 parts by weight of a polysiloxane having a siloxane structure of the following formulas (1) and (2): ##STR19## wherein R¹ is a C₁ to C₆ alkyl group or C₁ to C₂₁ acyl group, a is 1 to 200, b is 1 to 200, t is 2 or 3, and r is 1 to 100, formulated therein, and a softening agent and other rubber chemicals formulated therein.
 5. A tire tread rubber composition as set forth in claim 4, wherein 20 to 60 parts by weight of at least one filler selected from the group consisting of carbon blacks having a specific surface area by nitrogen adsorption (N₂ SA) of 50 to 170 m² /g and a dibutyl phthalate oil absorption (DBP) of 60 to 140 ml/100 g and 5 to 50 parts by weight of at least one filler selected from the group consisting of silicas having a specific surface area by nitrogen adsorption (N₂ SA) of 80 to 300 m² /g and a dibutyl phthalate oil absorption (DBP) of 100 to 300 ml/100 g are formulated.
 6. A tire tread rubber composition comprising 100 parts by weight of at least one rubber selected from the group consisting of styrene-butadiene copolymer rubbers having a styrene content of at least 10% by weight and 60 to 100 parts by weight of at least one filler selected from the group consisting of carbon blacks having a specific surface area by nitrogen adsorption (N₂ SA) of 50 to 170 m² /g and a dibutyl phthalate oil absorption (DBP) of 70 to 140 ml/100 g or other fillers, 5 to 50 parts by weight of a polysiloxane according to claim 2 and a softening agent and other rubber chemicals formulated therein.
 7. A tire tread rubber composition as set forth in claim 6, wherein 20 to 80 parts by weight of at least one filler selected from the group consisting of carbon blacks having a specific surface area by nitrogen adsorption (N₂ SA) of 50 to 170 m² /g and a dibutyl phthalate oil absorption (DBP) of 70 to 140 ml/100 g and 5 to 50 parts by weight of at least one filler selected from the group consisting of silicas having a specific surface area by nitrogen adsorption (N₂ SA) of 80 to 300 m² /g and a dibutyl phthalate oil absorption (DBP) of 100 to 300 ml/100 g are formulated.
 8. A rubber composition as set forth in claim 3, claim 5, or claim 7, wherein 2 to 150 parts by weight of a silica-containing polysiloxane master batch comprising 100 parts by weight of at least one ingredient selected from the group consisting of polysiloxanes having a siloxane structure of the following formulas (1) and (2): ##STR20## wherein R¹ is a C₁ to C₆ alkyl group or C₁ to C₂₁ acyl group, a is 1 to 200, b is 1 to 200, t is 2 or 3, and r is 1 to 100, containing 30 to 200 parts by weight of at least one filler selected from the group consisting of silicas having a specific surface area by nitrogen adsorption (N₂ SA) of 80 to 300 m² /g and a dibutyl phthalate oil absorption (DBP) of 100 to 300 mil/100 g is formulated.
 9. A rubber composition as set forth in claim 4 or claim 6, wherein 2 to 150 parts by weight of a carbon black-containing polysiloxane master batch comprising 100 parts by weight of at least one ingredient selected from the group consisting of polysiloxanes having a siloxane structure of the following formulas (1) and (2): ##STR21## wherein R¹ is a C₁ to C₆ alkyl group or C₁ to C₂₁ acyl group, a is 1 to 200, b is 1 to 200, t is 2 or 3, and r is 1 to 100, containing 30 to 200 parts by weight of at least one filler selected from the group consisting of carbon blacks having a specific surface area by nitrogen adsorption (N₂ SA) of 50 to 170 m² /g and a dibutyl phthalate oil absorption (DBP) of 60 to 140 ml/100 g or other fillers is formulated.
 10. A rubber composition as set forth in claim 3, claim 5, or claim 7, wherein 2 to 150 parts by weight of a silica- and carbon black-containing polysiloxane master batch comprising a mixture comprising 100 parts by weight of at least one ingredient selected from the group consisting of polysiloxanes having a siloxane structure of the following formulas (1) and (2): ##STR22## wherein R¹ is a C₁ to C₆ alkyl group or C₁ to C₂₁ acyl group, a is 1 to 200, b is 1 to 200, t is 2 or 3, and r is 1 to 100, containing 1 to 199 parts by weight of at least one filler selected from the group consisting of carbon blacks having a specific surface area by nitrogen adsorption (N₂ SA) of 50 to 170 m² /g and a dibutyl phthalate oil absorption (DBP) of 60 to 140 ml/100 g or other fillers and 1 to 199 parts by weight of at least one filler selected from the group consisting of silicas having a specific surface area by nitrogen adsorption (N₂ SA) of 80 to 300 m² /g and a dibutyl phthalate oil absorption (DBP) of 100 to 300 ml/100 g, wherein the sum of the two is 30 to 200 parts by weight, are formulated.
 11. A rubber composition as set forth in claim 8, wherein 2 to 190 parts by weight of a master batch containing 0.5 to 40% by weight, based on the silica content contained in the silica-containing polysiloxane master batch or silica- and carbon black-containing polysiloxane master batch, of a silane coupling agent is formulated.
 12. A rubber composition as set forth in claim 11, wherein 2 to 230 parts by weight of a master batch containing 0.05 to 30% by weight, based on the silane coupling agent content contained in the silica-containing polysiloxane master batch or silica- and carbon black-containing polysiloxane master batch, of a silanol condensation catalyst is formulated.
 13. A tire tread rubber composition as set forth in claim 4, wherein a silane coupling agent is further formulated in an amount of 5 to 30% by weight, based on the amount of silica formulated.
 14. A tire tread rubber composition as set forth in claim 13, wherein a silanol condensation catalyst is further formulated in an amount of 0.05 to 50% by weight, based on the amount of the silane coupling agent formulated.
 15. A rubber composition as set forth in claim 10, wherein 2 to 190 parts by weight of a master batch containing 0.5 to 40% by weight, based on the silica content contained in the silica-containing polysiloxane master batch or silica- and carbon black-containing polysiloxane master batch, of a silane coupling agent is formulated.
 16. A rubber composition as set forth in claim 15, wherein 2 to 230 parts by weight of a master batch containing 0.5 to 30% by weight, based on the silicane coupling agent content contained in the silica-containing polysiloxane master batch or silica- and carbon black-containing polysiloxane master batch, of a silanol condensation catalyst is formulated. 